1. Field of the Invention
The present invention relates to an ink jet recording apparatus for effecting recording on a recording medium by discharging ink from a recording means, and a cap for such an apparatus.
The present invention can be applied to an apparatus such as a printer, a copying machine, a facsimile having a communication system or a word processor having a printer portion for effecting recording on a recording medium such as a paper sheet, thread, fibers, cloth leather, metal, plastic, glass, wood or ceramics and to an industrial recording apparatus in which various processing devices are combined in a composite manner. Here, the word "recording" means not only to afford an image such as characters or figures which are meaningful to a recording medium but also to afford an image such as a pattern which is meaningless to a recording medium.
2. Related Background Art
An ink jet recording system has been used with printers and copying machines because of low noise, low running cost, easiness of compactness and easiness of colorization.
In the past, in ink jet recording apparatus, for the purpose of preventing ink clogging of discharge ports of a recording head due to solidification of ink or increase in ink viscosity caused by the drying of ink, the discharge ports of the recording head have been shielded from atmosphere, or, for the purpose of recovering clogging of discharge ports due to solidification of ink or increase in ink viscosity or bubbles or foreign matters generated in liquid passages, a suction recovering operation for forcibly discharging ink by generating pressure at the discharge openings has been performed. For example, as an example of such a suction recovering operation, a cap member is closely contacted with a discharge port surface of a recording head and ink is sucked from the recording head by generating negative pressure within the cap member and thereafter the ink remaining in the cap is sucked (idle suction) by communicating the interior of the cap with the atmosphere. Further, as another example, in order to prevent scattering of ink from the cap to the discharge ports of the recording head during the suction and to such the ink remaining around the discharge ports of the recording head, an ink absorbing member made of porous material for absorbing the ink is disposed within the cap member.
However, recently, in the ink jet recording systems, high quality recorded images have been requested and improvement in water-resistance and light-resistance of ink has been made. For example, various inks such as ink which becomes water-soluble (to water) after drying or ink including pigment as coloring agent have been used. Some of such inks increases its viscosity to loose fluidity (for example, becomes gel) after it is dried due to vaporization.
After an image was printed on a recording sheet by using the recording head utilizing the above-mentioned ink, if next recording is not effected for a long term, i..e, if the discharge ports of the recording head are kept in the sealed condition by the cap for a long term, small amount of ink remaining in the ink absorbing member after the previous suction recovery may be solidified in the ink absorbing member or may cause clogging. As a result, even when the suction recovery is effected to prepare for next recording, predetermined pressure does not act on the recording head not to suck the ink from the recording head sufficiently or the interior of the cap becomes hard to be communicated with the atmosphere not to achieve the suction of ink (idle suction), thereby not realizing the normal or optimum suction recovery.